The core kit
| Item | Job | Buying check | Budget note |
|---|---|---|---|
| Salt mix | The recurring chemistry input | Buy by stated litres produced, not bucket weight alone | £69.99–£89.99 examples for common 22–25 kg packs |
| RODI storage container | Holds source water before mixing | Food-safe, lidded and sized for your normal change volume | One-off cost varies by size and retailer |
| Mixing vessel + pump | Keeps saltwater moving | Dedicated, clean and strong enough for the vessel | Reuse lowers cost; keep it separate from dirty tank water |
| Heater | Brings replacement water near tank temperature | Use a guarded heater and verify with a separate thermometer | Equipment cost plus electricity |
| Refractometer / conductivity check | Confirms salinity before use | Calibrate with the correct standard and recheck after storage | Consumable calibration fluid is easy to forget |
| Tubing, siphon and spare seals | Moves water without leaks | Keep replacements before a maintenance day fails | Small recurring cost; model-specific fittings can cost more |
What is worth keeping as a spare?
Keep spare tubing, a basic transfer pump or siphon, replacement seals and calibration fluid. If your mixing pump is the only way to make water, a failed impeller can turn a routine change into an overnight delay. The sensible backup is the smallest one that prevents you improvising with dirty or unverified equipment.
Label the clean side
Mark containers, hoses and pumps for either clean RODI/saltwater or dirty aquarium water. This is cheap contamination control. Store dry salt with its lot information and note the date a new bucket was opened so an unusual result can be traced back to a product or batch.
Budget the year, not the basket
Start with your annual litres changed, multiply by the salt cost per litre, then add calibration fluid, replacement tubing, electricity and a small contingency for worn pumps or containers. This keeps the recurring cost visible when comparing a low-price salt with a more expensive product that may change your dosing or mixing routine.
Sources and limitations
Salt yields and mixing requirements were checked against Aquaforest’s official instructions and Red Sea’s mixing guide. Prices in the wider cluster are current UK examples, not a complete market survey. We have not tested any equipment.